I am trying to find references for the the Wikipedia article Frost line (astrophysics) I am having a hard time finding a reference for the "Sublimation temperature of water in vacuum" that is used for calculation of the current snow line. E.g.: I have found 150K in several places, without any reference. I understand that it is not a single point but a function of time, and probably 150K was chosen because it takes a long time (how long?) for X% of ice to sublime. Please try to give some hard reference (or calculation). Regards,QShadow.